代码: 全选
#include <unistd.h>
#include <stdio.h>
#include <fcntl.h>
#include <linux/fb.h>
#include <sys/mman.h>
int main () {
int fbfd = 0;
struct fb_var_screeninfo vinfo;
struct fb_fix_screeninfo finfo;
long int screensize = 0;
char *fbp = 0;
int x = 0, y = 0;
long int location = 0;
/* Open the file for reading and writing */
fbfd = open("/dev/fb0", O_RDWR);
if (fbfd < 0) {
printf("Error: cannot open framebuffer device.\n");
return -1;
}
printf("The framebuffer device was opened successfully.\n");
/* Get fixed screen information */
if (ioctl(fbfd, FBIOGET_FSCREENINFO, &finfo)) {
printf("Error reading fixed information.\n");
return -1;
}
/* Get variable screen information */
if (ioctl(fbfd, FBIOGET_VSCREENINFO, &vinfo)) {
printf("Error reading variable information.\n");
return -1;
}
/* Figure out the size of the screen in bytes */
screensize = vinfo.xres * vinfo.yres * vinfo.bits_per_pixel / 8;
/* Map the device to memory */
fbp = (char *)mmap(0, screensize, PROT_READ | PROT_WRITE, MAP_SHARED,
fbfd, 0);
if ((int)fbp == -1) {
printf("Error: failed to map framebuffer device to memory.\n");
return -1;
}
printf("The framebuffer device was mapped to memory successfully.\n");
x = 100; y = 100; /* Where we are going to put the pixel */
/* Figure out where in memory to put the pixel */
location = (x+vinfo.xoffset) * (vinfo.bits_per_pixel/8) +
(y+vinfo.yoffset) * finfo.line_length;
/* set RGBA value to the value */
*(fbp + location) = 0; /* Some blue */
*(fbp + location + 1) = 0; /* A little green */
*(fbp + location + 2) = 255; /* A lot of red */
*(fbp + location + 3) = 0; /* No transparency */
munmap(fbp, screensize);
close(fbfd);
return 0;
}
运行成功,但运行结果为什么没有图案显示呀